Understanding the characteristics of plaque is vital to the management of atherosclerosis. Given the noninvasive nature of Magnetic Resonance Imaging (MRI) and its many degrees of freedom, MRI offers the greatest potential for accurate evaluation of plaques and for following the disease process. During our initial three-year study, we created and developed an array of novel techniques for characterizing important plaque components. These techniques include: (1) a spectral-spatial pulse and a homodyne detection system for the robust spectroscopic separation of water and fat components, without requiring subtraction; (2) a novel imaging system for imaging ultra-short T2 components enabling the evaluation of fibrous tissue, cholesterol esters, etc; (3) a two-dimensional excitation system for selecting a deep-lying plaque volume, enabling high resolution imaging to determine surface character- istics, endothelial integrity, etc; (4) a system of correlative filtering, enabling high resolution imaging of weak components. In the proposed work, we will continue to develop techniques for short-T2 imaging of fibrous tissue in immobile lipid components and correlative filtering to provide high resolution images of the selected components, and 3-point Dixon methods for the separation of long-T2 components with high resolution. We will conduct in vitro tests of the new methods using plaques excised from human autopsy specimens, in vitro studies of plaque-related components at different magnetic field strengths, in vivo studies of atherosclerotic plaques in rabbit and dog models, and in vivo images of patients presenting for carotid endarterectomy. Correlations will be made between MR images, spectra, and histopathologic examination of the atherosclerotic specimens. The success of this work will yield a highly accurate characterization of atherosclerotic lesions and the disease process, and will lead to improved diagnosis and follow-up therapy.